1. Technical Field
The present invention relates to a sheet media feeding device and to a sheet media separation method for separating and feeding sheet media such as checks and printing paper one sheet at a time. The invention also relates to a sheet media processing device such as a check reading device, a printer, a scanner, or a magnetic reading device that has a sheet media feeding device.
2. Description of Related Art
In banks and other financial institutions checks and check-like instruments (negotiable securities) are passed through a check reader to read an image of the front of the check and the magnetic ink characters and sort the instruments based on the result of this reading operation. As electronic check processing has become more common, the scanned check image data and magnetic ink character data are processed by a computer and the check instruments are managed by computer. Check processing systems of this type are taught, for example, in JP2004-206362(A), US2004/0257626(A), and US2004/0251588(A).
In order to accurately read the check information, the checks must be fed one at a time and conveyed passed the reading position of the magnetic head that is used for magnetic ink character reading and the reading position of the scanner that is used to image the check. If plural checks are overlapping as they are transported, the information cannot be accurately read and the checks may jam in the transportation path.
Media separation methods for feeding checks and other sheet media that are held in a stack one sheet at a time include methods that separate the sheet media from the stack by pressing the sheet media against a separation pad that is made from a material with a high coefficient of friction while feeding the sheets, and methods (retard roller methods) that separate the sheet media by passing the media between a separation roller against which the media are pressed and a retard roller that applies a torque load. See, for example, JP2001-48362(A).
In JP2001-48362(A), which teaches a sheet media supply mechanism that is suitable for separating and feeding high rigidity sheets one at a time, a separation pad is pivotally supported so that the contact surface of the separation pad presses tightly against the surface of the sheets being fed from the cassette case and prevents the sheets from being fed in a bundle to the retard roller-type separation roller pair. The sheet that is in contact with the separation pad is not fed by the media separation mechanism taught in JP2001-48362(A) because the separation pad is pressed against the sheet. However, when plural sheets are stacked together it is still possible for sheets that are not in contact with the separation pad to be fed as a bundle to the separation roller pair due to the friction between the sheets.
If two overlapping sheets are fed together to the retard-roller-type separation roller pair, the sheet on the retard roller side is prevented from being fed and only one sheet is supplied from the separation roller pair. However, if three or more sheets are fed as a bundle into the separation roller pair, the one sheet in contact with the retard roller is prevented from being advanced but a plurality of the other sheets may pass as a stack through the separation roller pair without separating from each other due to the friction between the sheets.